This disclosure relates to breast compression paddles for use in mammography systems, including standard and tomosynthesis mammography systems.
Compression paddles for mammography have shapes that are generally optimized for patient comfort and for ease of positioning the breast during mammography. However, this optimization results in a compression paddle that has high lateral walls and a rigid metal frame, which is adverse to large angle (e.g., a total scanning angle of about 30 degrees to about 120 degrees) tomosynthesis imaging.
Tomosynthesis is a technique that allows the reconstruction of tomographic planes on the basis of the information contained in a series of projections acquired from a series of angular viewpoints about the target object (breast). They need not be regularly spaced, numerous, or arranged in any regular geometry. The tomosynthesis technique can provide improved spatial differentiation of nearby tissues at very high resolution comparable with projection 2D imaging. Tomosynthesis permits this to be accomplished while subjecting the patient to limited amounts of radiation.
The series of angular viewpoints about the breast (hereinafter “the object of interest”) can include angles of about ±15 degrees to about +/−60 degrees. However, the high lateral walls and the metal frame of the compression paddle obstruct the path of the x-ray beam and consequently a shadow from the high lateral walls and the metal frame is superimposed upon information obtained from the breast, which adversely affects the images of the breast. This obstruction can be clearly seen in the FIG. 1. FIG. 1 reflects a view of a compression paddle design that obstructs the x-rays during tomosynthesis imaging. As can be seen from the FIG. 1, a breast 100 is disposed between the compression paddle 10 and the detector 200 of the x-ray device. The compression paddle 10 lies between the detector 200 and an x-ray source 300. The compression paddle 10 comprises a paddle wall 20 and a paddle base 12. The paddle base 12 is fixedly attached to the paddle wall 20. In the depicted configuration, a largest vertical dimension of the paddle wall 20 is perpendicular to the paddle base 12. A bracket (not shown) provides support for the compression paddle 10 and permits the compression paddle to be displaced about a pivot point on the x-ray device. The pivot point is generally that point at which the bracket is in mechanical communication with the x-ray device. As can be seen from the FIG. 1, as the x-ray source 300 is rotated during tomosynthesis, at certain angles, the paddle wall obstructs the x-rays, and a shadow of the paddle wall, is projected onto the detector. This shadow is superimposed upon images of the breast, which is undesirable. Although reconstruction techniques may partially remove the above shadows, residual artifacts may be present in the images.
It is therefore desirable to have a compression paddle that does not obstruct images of the breast, while at the same time maintaining optimal patient comfort and permitting ease of positioning.